A wrapper is a program that internally calls another program and performs some further actions. For example, I could write a Perl script that run ls and changed the file sizes to hexadecimal.

So, based on your description, I think your program would be more like a filter than a wrapper. A filter is a program that takes the output of another program and modifies it in some way.

I suppose your script will be run either at the right side of a pipe (that is, simulator | your_script) or stand alone, in which case it would take the output from a log file or so. In any case, you'll have to read new lines as they are generated and act accordingly.

If you're at the right of a pipe, you read from STDIN as usual; if you have to work with a log, you can use File::Tail. For the XML I don't know but a search on CPAN will surely be enlightening.

UDP packet size is limited by the MTU of the network (tipically something between 400 and 1500bytes) and XML is very verbose and would probably generate messages larger than that.

So, first, ensure all your messages fit in UDP packets or send them over TCP or use a binary format to encode your data (for instance RPC).

#!/usr/bin/perl

use warnings;
use strict;

my $path = shift;

my $output = `dir $path`;

$output =~ s/DIR/FOO/g;

print $output;
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